DESCRIPTION

The etags program is used to create a tag table file, in a format
understood by
emacs(1)
; the ctags program is used to create a similar table in a
format understood by
vi(1)
. Both forms of the program understand
the syntax of C, Objective C, C++, Java, Fortran, Ada, Cobol, Erlang,
LaTeX, Emacs Lisp/Common Lisp, makefiles, Pascal, Perl, Postscript,
Python, Prolog, Scheme and
most assembler-like syntaxes.
Both forms read the files specified on the command line, and write a tag
table (defaults: TAGS for etags, tags for
ctags) in the current working directory.
Files specified with relative file names will be recorded in the tag
table with file names relative to the directory where the tag table
resides. Files specified with absolute file names will be recorded
with absolute file names.
The programs recognize the language used in an input file based on its
file name and contents. The --language switch can be used to force
parsing of the file names following the switch according to the given
language, overriding guesses based on filename extensions.

OPTIONS

Some options make sense only for the vi style tag files produced
by ctags;
etags does not recognize them.
The programs accept unambiguous abbreviations for long option names.

Tag files written in the format expected by vi contain regular
expression search instructions; the -B option writes them using
the delimiter `?', to search backwards through files.
The default is to use the delimiter `/', to search forwards
through files.
Only ctags accepts this option.

--declarations

In C and derived languages, create tags for function declarations,
and create tags for extern variables unless --no-globals is used.

-d,--defines

Create tag entries for C preprocessor constant definitions
and enum constants, too. This is the
default behavior for etags.

-D,--no-defines

Do not create tag entries for C preprocessor constant definitions
and enum constants.
This may make the tags file much smaller if many header files are tagged.
This is the default behavior for ctags.

-g,--globals

Create tag entries for global variables in C, C++, Objective C, Java,
and Perl.
This is the default behavior for etags.

-G,--no-globals

Do not tag global variables. Typically this reduces the file size by
one fourth. This is the default behavior for ctags.

-ifile, --include=file

Include a note in the tag file indicating that, when searching for a
tag, one should also consult the tags file file after checking the
current file. This options is only accepted by etags.

-I,--ignore-indentation

Don't rely on indentation as much as we normally do. Currently, this
means not to assume that a closing brace in the first column is the
final brace of a function or structure definition in C and C++.

-llanguage, --language=language

Parse the following files according to the given language. More than
one such options may be intermixed with filenames. Use --help
to get a list of the available languages and their default filename
extensions. The `auto' language can be used to restore automatic
detection of language based on the file name. The `none'
language may be used to disable language parsing altogether; only
regexp matching is done in this case (see the --regex option).

-m,--members

Create tag entries for variables that are members of structure-like
constructs in C++, Objective C, Java.

-M,--no-members

Do not tag member variables. This is the default behavior.

--packages-only

Only tag packages in Ada files.

-otagfile, --output=tagfile

Explicit name of file for tag table; overrides default TAGS or
tags. (But ignored with -v or -x.)

-rregexp, --regex=regexp

--ignore-case-regex=regexp

Make tags based on regexp matching for each line of the files
following this option, in addition to the tags made with the standard
parsing based on language. When using --regex, case is
significant, while it is not with --ignore-case-regex. May
be freely intermixed with filenames and the -R option. The
regexps are cumulative, i.e. each option will add to the previous
ones. The regexps are of the form:

/tagregexp[/nameregexp]/

where tagregexp is used to match the lines that must be tagged.
It should not match useless characters. If the match is
such that more characters than needed are unavoidably matched by
tagregexp, it may be useful to add a nameregexp, to
narrow down the tag scope. ctags ignores regexps without a
nameregexp. The syntax of regexps is the same as in emacs,
augmented with intervals of the form \{m,n\}, as in ed or
grep.
Here are some examples. All the regexps are quoted to protect them
from shell interpretation.

A regexp can be preceded by {lang}, thus restricting it to match
lines of files of the specified language. Use etags --help to obtain
a list of the recognised languages. This feature is particularly useful inside
regex files. A regex file contains one regex per line. Empty lines,
and those lines beginning with space or tab are ignored. Lines beginning
with @ are references to regex files whose name follows the @ sign. Other
lines are considered regular expressions like those following --regex.
For example, the command
etags --regex=@regex.file *.c
reads the regexes contained in the file regex.file.

-R,--no-regex

Don't do any more regexp matching on the following files. May be
freely intermixed with filenames and the --regex option.

-t,--typedefs

Record typedefs in C code as tags. Since this is the default behaviour
of etags, only ctags accepts this option.

-T,--typedefs-and-c++

Generate tag entries for typedefs, struct, enum, and union tags, and
C++ member functions. Since this is the default behaviour
of etags, only ctags accepts this option.

-u,--update

Update tag entries for files specified on command line, leaving
tag entries for other files in place. Currently, this is implemented
by deleting the existing entries for the given files and then
rewriting the new entries at the end of the tags file. It is often
faster to simply rebuild the entire tag file than to use this.
Only ctags accepts this option.

SEE ALSO

COPYING

Copyright
1999, 2001 Free Software Foundation, Inc.

Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.1
or any later version published by the Free Software Foundation;
with no Invariant Sections, with no Front-Cover Texts, and no
Back-Cover Texts.

This document is part of a collection distributed under the GNU Free
Documentation License. If you want to distribute this document
separately from the collection, you can do so by adding a copy of the
license to the document, as described in section 6 of the license.
A copy of the license is included in the
gfdl(1)
man page, and in the section entitled "GNU Free Documentation
License" in the Emacs manual.